SE1951382A1 - Remote sensor arrangement - Google Patents

Remote sensor arrangement

Info

Publication number
SE1951382A1
SE1951382A1 SE1951382A SE1951382A SE1951382A1 SE 1951382 A1 SE1951382 A1 SE 1951382A1 SE 1951382 A SE1951382 A SE 1951382A SE 1951382 A SE1951382 A SE 1951382A SE 1951382 A1 SE1951382 A1 SE 1951382A1
Authority
SE
Sweden
Prior art keywords
sensor
unit
sensor arrangement
cable
mode
Prior art date
Application number
SE1951382A
Inventor
Gunnar Klinghult
Lars-Ove Mogren
Magnus Fredholm
Original Assignee
Bombardier Transp Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bombardier Transp Gmbh filed Critical Bombardier Transp Gmbh
Priority to SE1951382A priority Critical patent/SE1951382A1/en
Priority to LTEP20210675.3T priority patent/LT3832321T/en
Priority to PL20210675.3T priority patent/PL3832321T3/en
Priority to AU2020280998A priority patent/AU2020280998A1/en
Priority to EP20210675.3A priority patent/EP3832321B1/en
Priority to DK20210675.3T priority patent/DK3832321T3/en
Priority to ES20210675T priority patent/ES2969294T3/en
Priority to US17/109,438 priority patent/US11372028B2/en
Publication of SE1951382A1 publication Critical patent/SE1951382A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/186—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using current transformers with a core consisting of two or more parts, e.g. clamp-on type
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
    • G01R15/202—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using Hall-effect devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
    • G01R15/207—Constructional details independent of the type of device used
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/003—Measuring mean values of current or voltage during a given time interval
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/58—Testing of lines, cables or conductors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B61—RAILWAYS
    • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
    • B61L1/00—Devices along the route controlled by interaction with the vehicle or train
    • B61L1/20—Safety arrangements for preventing or indicating malfunction of the device, e.g. by leakage current, by lightning
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B61—RAILWAYS
    • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
    • B61L27/00—Central railway traffic control systems; Trackside control; Communication systems specially adapted therefor
    • B61L27/50—Trackside diagnosis or maintenance, e.g. software upgrades
    • B61L27/53—Trackside diagnosis or maintenance, e.g. software upgrades for trackside elements or systems, e.g. trackside supervision of trackside control system conditions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)

Abstract

A stand-alone remote sensor arrangement (2) for monitoring parameter activity in a cable (4), the arrangement comprises a sensor unit (6) and a power source unit (8) connected to each other by a connecting cable (10), and a control unit (12),the power source unit (8) is configured to supply energy to said sensor unit (6), the sensor unit (6) comprises a shielded housing (14) enclosing a toroid-shaped core (16) configured to be fixed around the cable (4) to be monitored, andthe toroid-shaped core (16) is provided with at least one gap where a Hall sensor element (18) is arranged. The remote sensor arrangement (2) is configured to be operated in a low current consumption mode and in a measurement mode, in which measurement mode said Hall sensor element (18) is configured to sense a predetermined parameter activity, e.g. flowing current, of said cable (4), and that said control unit (12) is configured to change the mode of operation of said sensor arrangement (2). The sensor unit (6) further comprises a sensor activation unit (20) arranged and structured to sense parameters related to magnetic field variations in said core (16) caused by said parameter activity of said cable (2), and to generate a sensor activation signal (22) including parameter values dependent on said sensed parameters, wherein the control unit (12) is configured to receive said sensor activation signal (22) and to evaluate said parameter values in relation to predetermined mode changing criteria, and to change mode of operation of said sensor arrangement (2) dependent on the result of said evaluation.

Description

Remote sensor arrangement Technical fieldThe present disclosure relates to a remote sensor arrangement, and in particular to a stand-alone arrangement adapted to be applied for sensing activity in cables in any monitoring application and specif1cally in connection with railway implementations.
BackgroundA so-called Remote Sensor Unit (RSU) is typically used to monitor wayside and trackside objects health and functionality, in particular in relation to railways. The RSU providesmonitoring functionality for different types of objects and loads, e. g. wayside objects suchas Point Machines (PMs), Barrier Machines (BMs), aspect lights and other objects can bemonitored with the RSU.
Depending on the monitored object, different parameters can be tracked. For dynamicloads such as PMs, the RSU can be used to monitor duration of the switch movement butalso minimum, maximum, average and RMS current values of the movement. For staticloads such as aspect lights, the RSU can be used to track accumulated on-time and operational current levels.
A first generation of RSUs required cabling for measurement and powering.
The object of the present invention is to achieve a robust, stand-alone, Remote Sensor Unitcapable of measuring a wider range of AC/DC including low currents the presentlyapplied technology cannot measure. "Stand-alone" infers that it requires no extemal energy source and has a wireless communication interface to remote equipment.SummaThe above-mentioned object is achieved by the present invention according to the independent claim.
Preferred embodiments are set forth in the dependent claims.
According to an aspect of the present invention it relates to a stand-alone remote sensorarrangement 2 for monitoring parameter activity in a cable 4. The arrangement comprisesa sensor unit 6 and a power source unit 8 connected to each other by a connecting cable10, and a control unit 12. The power source unit 8 is configured to supply energy to saidsensor unit 6.
The sensor unit 6 comprises a shielded housing 14 enclosing a toroid-shaped core 16configured to be fixed around the cable 4, via a plastic fastener on the core housing, to bemonitored. The toroid-shaped core 16 is provided with at least one gap where a Hallsensor element 18 is arranged. The remote sensor arrangement 2 is configured to beoperated in a low current consumption mode and in a measurement mode, in whichmeasurement mode said Hall sensor element 18 is configured to sense a predeterrninedparameter activity, e. g. flowing current, of said cable 4, and that said control unit 12 isconfigured to change the mode of operation of said sensor arrangement 2.
The sensor unit 6 further comprises a sensor activation unit 20 arranged and structured tosense parameters related to magnetic field Variations in core 16 caused by parameteractivity of cable 4, and to generate a sensor activation signal 22 including parametervalues dependent on said sensed parameters. The control unit 12 is configured to receivesensor activation signal 22 and to evaluate parameter values in relation to predeterrninedmode changing criteria, and to change the mode of operation of sensor arrangement 2 dependent on the result of said evaluation.
Thus, the sensor arrangement, according to the present disclosure, relates to an RSU thatcontains a "wake-up" mechanism that activates the sensor unit between measurements,which allows significant savings on consumption of the battery. The sensor activation unit(sensing coil) measures a wide range of AC/DC currents including low value currents that the presently applied technology cannot measure.
In one embodiment the remote sensor arrangement 2 comprises a communication unit 30conf1gured to establish a bidirectional wireless communication link with an extemalequipment 32, and wherein said wireless communication link is a Bluetooth link, or any other robust wireless communication link, e.g. a wireless Intemet Protocol link. 3 Advantageously, the communication unit 30 is configured to send raw, non-processed,parameter values, e. g. current values, to said external equipment via said bidirectionalwireless communication link.
As such, the sensor arrangement does not need to have embedded intelligence from ananalytics point of view; it simply measures current and sends the values to an extemalelement of the system where analysis is performed. This is advantageous because dataprocessing circuitry is not required in the sensor arrangement, so saving energy and reducing the complexity of the circuitry.
Brief description of the drawings Figure l shows a schematic overview illustration of the sensor arrangement according tothe present invention.
Figure 2 is a block diagram that schematically illustrates the sensor arrangement accordingto the present invention.
Figure 3 is a schematic perspective view illustrating one embodiment of the sensorarrangement according to the present invention.
Figures 4-6 show various detail in relation to the sensor unit according to one embodimentof the present invention.
Figure 7 is an exploded view illustrating one exemplary variation of a sensor unit according to the present invention.
Detailed description The remote sensor arrangement will now be described in detail with references to theappended figures. Throughout the figures the same, or similar, items have the samereference signs. Moreover, the items and the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
First with reference to the schematic illustration in figure l a stand-alone remote sensorarrangement 2 is provided for monitoring parameter activity, e. g. flowing current, in acable 4. The arrangement comprises two separate units, a sensor unit 6 and a power sourceand communications unit 8 connected to each other by a connecting cable l0. With further references to figures 2 and 3, the sensor arrangement also comprises a control unit l2 arranged either in the sensor unit 6 or in the power source unit 8, or distributed in bothunits. The power source unit 8 is configured to supply energy to the sensor unit 6 and alsoto its own circuitry, and comprises a battery 9 and circuitry enclosed inside a battery housing.
The sensor unit 6 comprises a shielded housing 14 enclosing a toroid-shaped core 16configured to be fixed around the cable 4 to be monitored. The toroid-shaped core 16 is provided with at least one gap where a Hall sensor element 18 is arranged.
The remote sensor arrangement 2 is configured to be operated in a low currentconsumption mode and in a measurement mode. In the measurement mode the Hall sensorelement 18 is configured to sense a predeterrnined parameter activity, e. g. flowing current, of the monitored cable 4.
The control unit 12 is configured to change the mode of operation of the sensor arrangement 2.
The sensor unit 6 further comprises a sensor activation unit 20 arranged and structured tosense parameters related to magnetic field Variations in the core 16 caused by theparameter activity of the cable 4, and to generate a sensor activation signal 22 includingparameter values dependent on the sensed parameters.
The control unit 12 is configured to receive the sensor activation signal 22 and to evaluatethe parameter values in relation to predeterrnined mode changing criteria, and to change mode of operation of the sensor arrangement 2 dependent on the result of said evaluation.
According to an embodiment, one mode changing criterion relates to a derivate measure ofthe sensed parameters, and if the derivate measure exceeds a predeterrnined derivate threshold the mode of operation is changed to the measurement mode.
Preferably, the sensor activation unit 20 is a coil integrated in a printed circuit board(PCB) arranged in the housing. As an altemative, the sensor activation unit 20 is a coil that encircles a cross-sectional part of the core by being wound around the part of the core.
According to another embodiment, the toroid core 16 is divided into two semi-circularcore parts, and that said Hall sensor element 18 is provided in one of the gaps between end parts of the semi-circular core parts.
In a further embodiment the housing 14 comprises at least two housing shells, an outerhousing shell 24 made from a non-metallic material, and an inner housing shell 25,arranged within the outer housing shell and made from a shielding material capable ofelectrically and magnetically shield an inner cavity of the housing 14. The toroid core 16,the sensor activation unit 20, and the Hall sensor element 18 are arranged in the inner cavity of the housing 14.
Preferably, the housing 14 comprises two essentially equally sized parts, linked togetherby a hinge 26 and capable of being clamped around the cable 4, and e. g. snapped togetherand held in place by e.g. a plastic fastener. When the housing is mounted around the cablethe housing advantageously has a shape of a cylinder having an essentially circular cross-section. Other geometrical shapes are naturally possible, e. g. the housing may have a rectangular cross section when mounted around the cable, see figure 1.
In a further embodiment, the sensor activation unit 20, when the arrangement is operatedin the low current consumption mode, is capable of sensing current and to compare measured current values to a mode changing threshold.
In another embodiment, when the arrangement is operated in the measurement mode thesensor unit 6 is capable of performing measurement of current, being the parameteractivity, in the cable 4, and to generate a measurement signal 28 comprising current values dependent on measured current.
In one other embodiment, the remote sensor arrangement 2 comprises a communicationunit 30 configured to establish a bidirectional wireless communication link with anextemal equipment 32. The wireless communication link is a Bluetooth link, or any other wireless communication link, e.g. a Wireless Intemet Protocol link.
The external equipment 32 may be arranged Within a distance from the sensorarrangement 2 that secures that the chosen method, e. g. Bluetooth, of Wirelesscommunication may be achieved. The extemal equipment is provided With the requiredcommunication capability to establish and perform bidirectional communication to thesensor arrangement. Preferably, it should also be provided With a processing capability to perform analysis of the received measurement signal 28.
Preferably, the communication unit 30 is configured to send raw, non-processed,parameter values, e.g. current values, to the extemal equipment via the bidirectionalWireless communication link. Thus, no processing circuitry is required in the sensorarrangement, instead, further signal processing is performed extemally, e. g. in the extemalequipment. The further signal processing may relate to e.g. calculating the RMS, Max,Min, Mean and sWitching time based upon the current flowing through the cable during the sWitching period.
In a further embodiment the sensor unit 6 comprises a temperature sensor 34 configured tosense a temperature in relation to said sensor unit 6, and to generate a temperature signal to be applied to the control unit 12.
According to one embodiment the control unit 12 is configured to receive an extemallygenerated mode changing signal including a mode changing command, and to changeoperation mode of the sensor arrangement in dependence of the mode changing command.The mode changing command may then be generated at predeterrnined time intervals, Which e. g. is applicable for measurements in relation to track circuits.
Preferably, the control unit 12 is configured to activate the measurement mode for apredeterrnined time period, e. g. in the range of 0.5 - 2.0 seconds, and Wherein during that time period the mean current is measured.
The remote sensor arrangement 2 may be used for monitoring current in cables in many different applications Where remote monitoring is required, e. g. in remote places or in 7 onerous conditions. Particularly, as mentioned above, the arrangement is structured tomonitor cables applied in railway applications, e.g. for supplying power to point machines and track circuits.
The power source unit 8 comprises the power source, eg. a battery, arranged within apower source unit housing. In one exemplary variant the following prerequisites are to befulf1lled by the power source unit. The battery life-time shall be at least 7 years at 15degrees centigrade when applied with a sensor unit that perforrns and communicatesmeasurements every two minutes. The type of battery has preferably the followingoperational data: 3.6V, size C, and 8.5Ah. The power source unit housing shall not haveany metal parts and is preferably made from a plastic material. Preferably, the communication unit 30, arranged within the power source unit 8, is a Bluetooth module.
The mechanical concept design of the sensor unit 6 is advantageously made with thefollowing prerequisites and input. The physical outer housing shell does not include anymetal parts on the exterior. The sensor unit 6 is structured to measure the current in a cablewith a diameter of 2mm to 4mm without modifying the cable integrity and properties.Thus, it is not necessary to cut or remove any cables to install a sensor unit, and theinstallation shall not require any special tools. The measurements performed by the sensorunit are not affected by or affect other objects or nearby systems. This is secured by the shielding inner housing shell 25.
The electronics, e.g. the control unit 12, of the sensor unit 6 will advantageously bearranged on a printed circuit board (PCB) within the housing. A PCB is illustrated in the examples shown in figures 5-7.
As discussed above, the current is measured with a Hall sensor element, allowingmeasurement of both AC and DC. The signal from the Hall-sensor is low pass f1ltered toremove any high frequency content before it is fed to a 16-bit AD converter and thenapplied to the control unit. Several different types of Hall sensor elements may be applied.
Calculations on the needed sensitivity have been carried out, and these calculations together with practical tests have given a desired sensitivity of the Hall sensor element in the range of 50 - 100 mV/MT.
Generally, a Hall sensor is a device that is used to measure the magnitude of a magneticfield. Its output voltage is directly proportional to the magnetic field strength through it, and is used e. g. for current sensing applications.
According to one embodiment, a temperature sensor 34 is located close to the Hall sensorelement, e. g. arranged at the PCB, to be able to monitor the temperature. It will then be possible to compensate the sensitivity of the system for different temperatures.
Preferably, the wake-up function is performed by the sensor activation unit that e.g.consists of a coil and signal processing electronics. The coil senses any transient current(di/dt) in the cable. This signal will be amplif1ed, band pass f1ltered and used to generatean interrupt that wakens the system. It is important that the total wake-up time is short as itwill not be possible to collect any data during this time. A pulse stretcher part makes avery short transient pulse longer making sure that the interrupt input of the processor cancatch it.
The current consumption of the wake-up function needs to be very low as this partremains continuously active. It is specified to be below 50 uA.
Two different embodiments of the sensor activation unit are applied. The coil may eitherbe a conventional wire wound or made on a PCB. The PCB solution is most cost efficient when also the sensor and electronic components are located on the same PCB.
In one variation a toroid core is applied with the dimensions 22/ 14/ 13 mm, that is cut intwo equally sized halves. With regard to the core material specif1cation, the parametercoercive force is important to get as low hysteresis as possible. It should be as low aspossible and not have a non-linear variation with temperature. Another importantparameter is the perrneability, which should have a linear behaviour over the temperature range.
The conclusion from above tests is that the geometry of the core is important When itcomes to reducing impact from extemal magnetic fields and a toroid core is thereforepreferred.
The toroid should not have a bigger diameter than necessary as this makes it moresensitive to extemal magnetic fields. The minimum diameter is set by the outer diameterof monitored cables plus some mechanical restrictions. It also shows that a bigger lengthof the toroid is better When it comes to suppressing extemal magnetic fields.
The desired air-gap is in the range of 2 - 4 mm in total.
With regard to materials for the toroid core several different ferrite materials may beconsidered. The parameter coercive force is important, to get as low hysteresis as possible.Another important parameter is the perrneability, to have a linear behaviour over the temperature range.
Thus, the complete current sensor unit comprises a core (concentrator), a Hall sensorelement and a sensor activation unit, e. g. a coil. The core concentrates and amplif1es theinduced field from the cable to be monitored. In an air-gap the Hall-sensor element ismounted. This sensor senses both AC and DC current. The sensor activation unit is onlysensing changes in the current and is used for Waking up the Who le arrangement, When performing Event Initiated Measurement (EIM).
The sensor unit Works according to an open loop principle. The reason for this is cost andcomplexity. A closed loop sensor Will consume additional energy as this is an activesystem With current feedback. The complexity Will cost more in both components countand develop time. Thus, the object is to be able to monitor measurements that relate bothto type l (tracking circuit = lA) and type 2 (point machine = 10A) by the same sensor unit.
In one embodiment of the sensor activation unit, a Wake-up coil is provided With 200 tumsthat may detect a transient current of 200 mA. The sensitivity can easily be adjusted by the number of Windings on the coil or in the gain of the amplifier. As this coil is only sensitive to AC there is no DC offset Which means that it is possible to Work With high gain Withoutthe risk for saturation of the amplifier.
The size of the air-gap Where the Hall sensor is arranged only marginally affects thesensitivity of the coil. The core material has a much bigger influence of the sensitivity.The coil senses any transient current (di/dt) in the cable. The sensor activation signal 22 isapplied to the control unit 12 Where it Will be amplified, filtered and used to generate aninterrupt that Wakens the system. It is important that the total Wake-up time is minimal asit Will not be possible to collect any data during this time. It is estimated that the start-uptime for the processor in the control unit Will be beloW 2 ms and it is important that themajor part of this is not coming from the sensor.
A calculation on the noise margin of the coil and amplifier together shows that theamplifier Will set the noise level but it Will not be critical. As an example, an operationalamplifier With a noise level in the area of 20 nV/sqr Hz may be used.
As mentioned above, there are different solutions regarding hoW to realize the coil. Thecoil may either be a conventional coil or made on one or several PCBs. The PCB solution may be more cost efficient because also the Hall sensor may be arranged at the same PCB.
The sensor unit includes a magnetic shielding Which is provided by the inner housing shell25. This may be achieved in several Ways. The Whole core can be shielded or just partlyshielded, or a tubular shield. The Hall sensor element is itself sensitive to an extemal fieldand should also be shielded. The shielding material may be mild steel or mu-metal. In onevariation mild steel is applied and the thickness is around 0.3 mm. The shielding needs tobe efficient from DC to some tenths of kHz. The material must not be saturated. Theshielding inner housing shell 25 is arranged at a predeterrnined distance from the core, e.g.more than 5mm, so that the shield does not have a magnetic coupling to the core,otherwise this Will negatively affect the hysteresis of the core. The different shields do notneed to be in electric contact With each other but they need to overlap.
Generally, the sensor unit 6 itself needs to be rigidly mounted and immobile. If the sensorunit can move it Will cause an error in the sensors offset due to the geomagnetic field. Thecable 4 should be tightly clamped in the concentrator through-going opening defined by the toroid core 16. This may be achieved by flexible pads structured to centre the cable in ll the opening. If the cable has the possibility to move this has a potential for error in the measurement.
In one exemplary version of the sensor unit 6 the core snaps down in the shielding innerhousing shell 25 where it is fixed by ribs and snaps, see figure 4. To manage the ferritecore tolerances a foam spacer might be necessary to place under the core so the necessaryair gap is fialfilled. The connecting cable 10 is then connected to the PBA. In thisexemplary version the PCB includes a built in coil with several tums that extends aroundthe core, for the wake-up function. The PBA also includes analogue components, a rigidflex with the hall sensor element, a temperature sensor and a cable connector. As shown infigure 5 the PBA is provided with two openings located at positions and havingdimensions that enables the PBA to be mounted such that the core will extend through theopenings. This is advantageous in that the Hall sensor may be positioned in the gapbetween the two core parts by means of the rigid flex and also that the circuitry at the PCBwill be shielded by the inner housing shell.
The PBA is then snapped down in inner housing shell and the sensor flex are mounted onthe core with adhesive, see figure 6.
An exploded view of the entire sensor unit 6 is shown in figure 7. In figure 7 is shown theessential parts previously discussed, and in addition further details required to mount thevarious parts together and also flexible paddings used to firmly hold the cable to bemonitored in a fixed position. Specifically, the air gap where the Hall sensor element is tobe mounted between the core-core is critical, and therefore, in order to secure apredeterrnined gap distance a spring might be required to push the core down against one or many spacers.
The dimensions of the above disclosed exemplary sensor unit is 40*40*30 mm (40*45*30with snap and living hinge included). The size depends e. g. on size and amount of component that need to be on the PCB, and the space for the built in coil on the PCB.
According to one variation of the connecting cable 10, it has a diameter of 3.3 mm and is typically at least 700 mm long. Other lengths and dimensions are naturally possible. The 12 cable shall be shielded. On the cable there shall be a cable gland on each side, for strain relief and sealing.
The main application is measuring driving electrical power to point machines and trackcircuits. There are numerous further applications and industries where the remote sensorarrangement may be used. Its purpose is long terrn predictive analysis as it senses a trendin current drawn. For example, when used with a point machine, the sensor unit of theremote sensor arrangement is clamped around the power supply cable to the pointmachine. The sensor activation unit senses that the point machine is activated by sensingthe voltage induced in the sensor unit when there is current in the cable, then the mainmeasurement is triggered. The sensor arrangement does not send any alarrns but generatesand wirelessly transmits the raw measurement signal to an extemal element of the systemwhere the gathered data is analysed and may be acted upon. For a point machine the RMS,Max, Min, Mean and switching time is calculated based on the current flowing through theclamp during the switching period.
Track circuits are measured at configurable time intervals, they are not activated by anycurrent induced event, i.e. the sensor doesn°t know if there°s a train occupying the track.For track circuits only the mean current is measured for approximately l second; thisvalue is later used for long-terrn predictive analysis purposes.
For water pumps protecting signalling equipment rooms, the remote sensor arrangement provides low-cost power supply monitoring similar to the examples above.
The measurement of the predeterrnined parameter activity in the cable performed by thesensor unit may be initiated in two different ways. Either an Event Initiated Measurement (EIM), or a Time Initiated Measurement (TSIM).
The EIM measurement is started when the sensor activation unit, e. g. the coil, in thesensor unit senses transient activity, e. g. from increased current, in the cable. Theactivation unit then produces a short pulse that is used to wake up the sensor unit.
The current off/on event creates a detectable slope (positive and/or negative as needed)which is used to wake up the sensor from sleep. The sensor samples windows of n samples and calculates the RMS value. When z consecutive window RMS values are larger than a 13 predeterrnined start_thresh0ld, the Waveforrn Will be saved. The sampling is ended When zconsecutive Windows are lower than a predeterrnined st0p_thresh0ld.
The parameters n, start_thresh0ld, st0p_thresh0ld and z are configurable.
The TSIM measurement is done on timed intervals specified in the device configuration.When the sensor Wakes up for a measurement it sample n samples With a separation of t(ms). To save battery the sensor Will sleep between the n samples.
The parameters n, tand varíance_thresh0ld are configurable.
The present invention is not limited to the above-described preferred embodiments.Various altematives, modifications and equivalents may be used. Therefore, the aboveembodiments should not be taken as limiting the scope of the invention, Which is defined by the appending claims.

Claims (15)

14 m
1. A stand-alone remote sensor arrangement (2) for monitoring parameteractivity in a cable (4), the arrangement comprises a sensor unit (6) and a power source unit(8) connected to each other by a connecting cable (10), and a control unit (12), the power source unit (8) is configured to supply energy to said sensor unit (6), the sensor unit (6) comprises a shielded housing (14) enclosing a toroid-shaped core (16)configured to be fixed around the cable (4) to be monitored, and the toroid-shaped core (16) is provided with at least one gap where a Hall sensor element(18) is arranged, c h a r a c t e r i z e d in that the remote sensor arrangement (2) isconfigured to be operated in a low current consumption mode and in a measurementmode, in which measurement mode said Hall sensor element (18) is configured to sense apredeterrnined parameter activity, e. g. flowing current, of said cable (4), and that saidcontrol unit (12) is conf1gured to change the mode of operation of said sensor arrangement(2), the sensor unit (6) further comprises a sensor activation unit (20) arranged and structuredto sense parameters related to magnetic field variations in said core (16) caused by saidparameter activity of said cable (4), and to generate a sensor activation signal (22)including parameter values dependent on said sensed parameters, wherein the control unit(12) is conf1gured to receive said sensor activation signal (22) and to evaluate saidparameter values in relation to predeterrnined mode changing criteria, and to change mode of operation of said sensor arrangement (2) dependent on the result of said evaluation.
2. The remote sensor arrangement (2) according to claim 1, wherein one modechanging criterion relates a derivate measure of said sensed parameters, and if the derivatemeasure exceeds a predeterrnined derivate threshold the mode of operation is changed to the measurement mode.
3. The remote sensor arrangement (2) according to claim 1 or 2, wherein saidsensor activation unit (20) is a coil integrated in a printed circuit board arranged in said housing.
4. The remote sensor arrangement (2) according to claim 1 or 2, wherein said sensor activation unit (20) is a coil that encircles a cross-sectional part of said core by being wound around said part of the core.
5. The remote sensor arrangement (2) according to any of claims 1-4, whereinthe toroid core (16) is divided into two semi-circular core parts, and that said Hall sensorelement (18) is provided in one of said gaps between end parts of said semi-circular core parts.
6. The remote sensor arrangement (2) according to any of claims 1-5, whereinsaid housing (14) comprises at least two housing shells, an outer housing shell (24) madefrom a non-metallic material, and an inner housing shell (25), arranged within said outerhousing shell and made from a shielding material capable of electrically and magneticallyshield an inner cavity of said housing (14) where said toroid core (16), said sensor activation unit (20), and said Hall sensor element (18) are arranged.
7. The remote sensor arrangement (2) according to any of claims 1-6, whereinsaid housing (14) comprises two essentially equally sized parts, linked together by a hinge(26) and capable of being clamped around said cable (4), and wherein when mountedaround said cable said housing has a shape of a cylinder having an essentially circular cross-section.
8. The remote sensor arrangement (2) according to any of claims 1-7, whereinwhen in said low current consumption mode the sensor activation unit (20) is capable of sensing current and to compare measured current values to a mode changing threshold.
9. The remote sensor arrangement (2) according to any of claims 1-8, whereinwhen in said measurement mode the sensor unit (6) is capable of performing measurementof current, being said parameter activity, in said cable (4), and to generate a measurement signal (28) comprising current values in dependence of measured current.
10. The remote sensor arrangement (2) according to any of claims 1-9, comprising a communication unit (30) conf1gured to establish a bidirectional wireless 16 communication link With an external equipment (32), and Wherein said Wirelesscommunication link is a Bluetooth link, or any other Wireless communication link, e.g. a Wireless Intemet Protocol link.
11. The remote sensor arrangement (2) according to claim 10, Wherein saidcommunication unit (3 0) is configured to send raw, non-processed, parameter Values, e. g.current Values, to said extemal equipment Via said bidirectional Wireless communication link.
12. The remote sensor arrangement (2) according to any of claims 1-11, Whereinsaid sensor unit (6) comprises a temperature sensor (34) configured to sense a temperaturein relation to said sensor unit (6), and to generate a temperature signal (3 6) to be applied to said control unit (12).
13. The remote sensor arrangement (2) according to any of claims 1-12, Whereinthe control unit (12) is configured to receive an extemally generated mode changing signalincluding a mode changing command, and to change operation mode of the sensor arrangement dependent on the mode changing command.
14. The remote sensor arrangement (2) according to any of claims 1-13, Whereinsaid control unit (12) is configured to activate said measurement mode for a predeterrninedtime period, e. g. in the range of 0.5 - 2.0 seconds, and Wherein during said time period the mean current is measured.
15. The remote sensor arrangement (2) according to any of claims 1-14, Whereinsaid arrangement is structured to monitor cables applied in railway implementations, e. g. for supplying poWer to point machines and track circuits.
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AU2020280998A AU2020280998A1 (en) 2019-12-03 2020-11-30 Remote sensor arrangement
EP20210675.3A EP3832321B1 (en) 2019-12-03 2020-11-30 Remote sensor arrangement
DK20210675.3T DK3832321T3 (en) 2019-12-03 2020-11-30 REMOTE SENSOR DEVICE
ES20210675T ES2969294T3 (en) 2019-12-03 2020-11-30 Remote Sensor Arrangement
US17/109,438 US11372028B2 (en) 2019-12-03 2020-12-02 Remote sensor arrangement

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